Formation and structure of food bodies in Cordia nodosa (Boraginaceae).

Cordia nodosa Lamark (Boraginaceae) is a myrmecophyte (i.e., plants housing ants in hollow structures) that provisions associated ants with food bodies (FBs) produced 24 h a day. Distributed over all the young parts of the plants, they induce ants to forage continually and so to protect the plants. Metabolites are stored in the inner cells of C. nodosa FBs as they form. In addition the peripheral cells have an extrafloral nectary-like function and secrete a substance that covers the FBs. The amalgam of these two functions, distinct in other known cases, is discussed taking into account the origin of FBs and extrafloral nectaries.

Insect behaviour: arboreal ants build traps to capture prey.

To meet their need for nitrogen in the restricted foraging environment provided by their host plants, some arboreal ants deploy group ambush tactics in order to capture flying and jumping prey that might otherwise escape. Here we show that the ant Allomerus decemarticulatus uses hair from the host plant's stem, which it cuts and binds together with a purpose-grown fungal mycelium, to build a spongy 'galleried' platform for trapping much larger insects. Ants beneath the platform reach through the holes and immobilize the prey, which is then stretched, transported and carved up by a swarm of nestmates. To our knowledge, the collective creation of a trap as a predatory strategy has not been described before in ants.

Genome-wide identification of in vivo Drosophila Engrailed-binding DNA fragments and related target genes.

Chromatin immunoprecipitation after UV crosslinking of DNA/protein interactions was used to construct a library enriched in genomic sequences that bind to the Engrailed transcription factor in Drosophila embryos. Sequencing of the clones led to the identification of 203 Engrailed-binding fragments localized in intergenic or intronic regions. Genes lying near these fragments, which are considered as potential Engrailed target genes, are involved in different developmental pathways, such as anteroposterior patterning, muscle development, tracheal pathfinding or axon guidance. We validated this approach by in vitro and in vivo tests performed on a subset of Engrailed potential targets involved in these various pathways. Finally, we present strong evidence showing that an immunoprecipitated genomic DNA fragment corresponds to a promoter region involved in the direct regulation of frizzled2 expression by engrailed in vivo.